1. Field of the Invention
The present invention relates to a pipe coupling comprising a male coupling member and a female coupling member, which are coupled by being fitted to each other. More particularly, the present invention relates to a pipe coupling used in a situation in which the male and female coupling members as coupled together are likely to become difficult to decouple (separate) from each other due to freezing.
2. Description of Related Art
At a hydrogen supply station where hydrogen is supplied to a hydrogen automobile, for example, the supply of hydrogen is carried out by using a female coupling member (socket) and a male coupling member (plug), which are coupled to each other. The female coupling member is provided at the distal end of a supply hose extending from a station tank storing gaseous or liquid hydrogen at high pressure and at low temperature. The male coupling member is provided at the outer end of a hydrogen receiving pipe of a hydrogen storage tank mounted in the hydrogen automobile. Therefore, there is a possibility that the coupled female and male coupling members may be frozen during the supply of hydrogen, causing the moisture in the surrounding air to condense and freeze on the mutually contacting surfaces of the female and male coupling members, making it difficult to decouple the female and male coupling members from each other. Even if the fluid to be handled is not at such a low temperature, a similar problem can occur to the female and male coupling members coupled by being fitted to each other in an extremely cold region. A similar problem can also occur between a female coupling member and a locking element-actuating sleeve slidably fitted over the outer circumferential surface of the female coupling member so as to be movable between a position for engaging locking elements with a male coupling member to securely connect the male coupling member to the female coupling member and a position for allowing the locking element to be disengaged from the male coupling member.
There have been developed various techniques to solve the above-described problem due to freezing. For example, Japanese Patent Application Publication No. 2006-266336 discloses an electromagnetic valve in which, when an electromagnetic coil is not energized, a movable core is placed close to a stator core with a gap provided therebetween to prevent freezing between the movable and stator cores, thereby allowing the movable core to move smoothly when the electromagnetic coil is energized.